<h2>Primitive types</h2>
<pre><code>function method(x: number, y: string, z: boolean) {}
function stringifyBasicValue(value: string | number) {}
function add(one: any, two: any): number {
  return one + two;
}

const bar: number = 2;
var barVar: number = 2;
let barLet: number = 2;
let isOneOf: number | boolean | string = foo;</code></pre>

<h2>Keywords</h2>
<pre><code>type UnionAlias = 1 | 2 | 3;
opaque type ID = string;
declare opaque type PositiveNumber: number;
type Country = $Keys&lt;typeof countries>;
type RequiredProps = $Diff&lt;Props, DefaultProps>;</code></pre>